The present invention relates to a tape tension regulator, and more particularly to a tape tension regulator for automatically adjusting for minute variations of tension which have heretofore been difficult to control with conventional tape tension regulators, thereby providing improved picture and sound qualities when applied to electronic apparatuses.
In electronic apparatuses for recording and reproducing information using a magnetic tape as a medium, there are several factors which ultimately determine picture and sound qualities. For example, besides the inferiority of various electronic components and circuit devices constituting an electronic appliance, which undoubtedly result in poor picture and sound qualities, an improper voltage supply, the electromagnetic influence of nearby high-voltage cables, and deteriorated magnetic tape can be given as contributors. In addition to these, certain trivial factors may have a significant affect; one being tension of the magnetic tape. In other words, while performing rotational motion, rectilinear motion or a certain curvilinear motion combining the two, the magnetic tape in an electronic apparatus as above contacts a guide roller and various poles installed along its travelling path, to thereby cause friction between these, which thus applies tension to the tape. Here, if, for some reason, an unnecessarily burdensome or, contrarily, a too slight tension is applied, the tape speed becomes irregular, making the detected signal amount vary per predetermined time periods. As a result, a highly clear picture quality and/or sound quality cannot be obtained. This mechanism in connection with the tension on a tape is illustrated in FIG. 1.
FIG. 1 schematically shows a conventional tape tension regulator, wherein a tape 1 travels by way of a supply-reel 7, a tension pole 3 and a guide roller 2. At this time, tape 1 is held taut by the tension which is increased when tape 1 passes the guide device, i.e., tension pole 3 and guide roller 2. The tension becomes increased especially when the contact surface is a common fixed-type contact surface, like tension pole 3 which is not a roller. In this state, if the tension applied to tension pole 3 is stronger than a proper tension, tension pole 3 is forced in the direction of an arrow D, so that a tension arm 4 connected to tension pole 3 is rotated clockwise around a rotating shaft P overcoming the resilient force of spring 8. Then, a tension band 5 connected to tension arm 4 loosens, thus releasing a brake lining 6 attached thereto, which facilitates the rotation of supply-reel 7. Therefore, the overly strong tension is weakened. Meanwhile, if the tension applied to tension pole 3 is weaker than the proper tension, tension arm 4 rotates counter-clockwise by means of the elastic restoring force of tension spring 8 to thereby draw tension band 5, so that brake lining 6 is tightened to brake the rotation of supply-reel 7 to some degree. By this operation, the relatively weak tension is strengthened, thereby maintaining the proper level.
As described above, the conventional tension regulator serves for automatically adjusting the tape tension by means of the elasticity of tension spring 8. However, the tension applied to the tape is wholly increased across the tape according to the variations of the tape take-up state, i.e., according to the progress from the initial, middle to last stag of the take-up. Also, even though insignificant, the tension inevitably varies due to external disturbances and accuracy of supply-reel 7. This slightly varied tension cannot be controlled by the conventional tension regulator.